Applications herefor are found, for example, in cases in which persons must move forward in environments that are difficult to see into or make orientation difficult in another way, for example, to find the way back. Such an application may concern, for example, a fireman, who must move through an unknown area and/or an environment in which visibility is greatly restricted and must find the way back later. It may also be necessary in an emergency for another fireman to retrace the path traveled in order to rescue the first one.